双偏振天气雷达水平和垂直通道回波对比
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摘要
本文针对南京溧水S波段双偏振多普勒天气雷达获取的回波I/Q信号,采用FFT算法处理水平和垂直通道I/Q数据,分别得到水平和垂直通道回波的强度、速度值,定性分析了两通道回波强度、速度数据差异,引入平均差及均方根误差参数做定量分析。对比结果表明:两通道I/Q数据处理得到的回波层次分布基本一致;两通道速度数据差异较小,强度数据差异较大。以水平通道回波数据为基准,当回波强度小于16 dBz时,水平通道强度偏小,这可能是由云系边缘较小的针状冰晶所致;当回波强度大于32 dBz时,水平通道强度值偏大,且随回波强度的增加两通道强度差值增大,这反映了强降水中大粒子较多,而粒子越大,降落过程中扁平程度越大;两通道回波强度的差值与回波强度大小呈现一定相关性,这可能反映了单偏振天气雷达在定量测量降水中精度不高,通过双偏振雷达联合利用两通道数据有望改善雷达定量测量降水精度,提升雷达定量估测降水能力。
FFT algorithm was used to process the horizontal and vertical channel I/Q signals received from S-band dual-polarization Doppler weather radar in Lishui, Nanjing. The intensity and velocity data of two channels were obtained. We made a qualitative analysis of the differences of echo intensity and velocity data between two channels, and used the mean difference and root mean square error parameters for quantitative analysis. Comparison results show that the echo distribution obtained from I/Q data are basically the same between two channels. The difference of two channels' velocity data is small, while the difference of intensity data is large. Taking the echo data of the horizontal channel as the reference, when the echo intensity is less than 16 dBz, the horizontal channel intensity is relatively small, which may be caused by smaller acicular crystals at the cloud edge; when the echo intensity is greater than 32 dBz, the horizontal channel intensity is large, and with the increasing of the echo intensity, the intensity value difference increases between the two channels. This reflects that the heavy precipitation has more large particles, and the larger the particles, the more flattened during the landing. A certain relevance of intensity value difference and intensity between two channels is presented. This may reflects that the quantitative measurement of precipitation by the single polarization weather radar is not high in accuracy, and in the joint use of data of thetwo channels by the dual-polarization radar is expected to improve the accuracy and capability of radar quantitative measurement of precipitation.
FFT algorithm was used to process the horizontal and vertical channel I/Q signals received from S-band dual-polarization Doppler weather radar in Lishui, Nanjing. The intensity and velocity data of two channels were obtained. We made a qualitative analysis of the differences of echo intensity and velocity data between two channels, and used the mean difference and root mean square error parameters for quantitative analysis. Comparison results show that the echo distribution obtained from I/Q data are basically the same between two channels. The difference of two channels' velocity data is small, while the difference of intensity data is large. Taking the echo data of the horizontal channel as the reference, when the echo intensity is less than 16 dBz, the horizontal channel intensity is relatively small, which may be caused by smaller acicular crystals at the cloud edge; when the echo intensity is greater than 32 dBz, the horizontal channel intensity is large, and with the increasing of the echo intensity, the intensity value difference increases between the two channels. This reflects that the heavy precipitation has more large particles, and the larger the particles, the more flattened during the landing. A certain relevance of intensity value difference and intensity between two channels is presented. This may reflects that the quantitative measurement of precipitation by the single polarization weather radar is not high in accuracy, and in the joint use of data of thetwo channels by the dual-polarization radar is expected to improve the accuracy and capability of radar quantitative measurement of precipitation.
引文
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[8] 孙宁,寿绍文,吴海英,等.用二步变分法反演的单多普勒雷达风场研究中尺度暴雨.气象科学,2009,29(6):768-774.SUN Ning,SHOU Shaowen,WU Haiying,et al.Meso-scale rainstorm analysis by retrieved wind field from single Doppler radar using twi-adjoint method.Scientia Meteorologica Sinica (in Chinese),2009,29(6):768-774.
[9] Gorgucci E,Scarchilli G,Chandrasekar V.A procedure to calibrate multiparameter weather radar using propertiesof the rain medium.IEEE Trans.Geosci.Remote.Sens.,1999,37(1):269-276.
[10] Gourley J J,Tabary P,Chatelet J P D.Data quality of the Meteo-France C-band polarimetric radar.J.Atmos.Ocean.Technol.,2006,23(10):1340-1356.
[11] 吴林林,刘黎平,袁野,等.C波段车载双偏振雷达ZDR资料处理方法研究.高原气象,2015,34(1):279-287.WU Linlin,LIU Liping,YUAN Ye,et al.Study on ZDR processing algorithm of C-band mobile dual polarization radar.Plateau Meteorology (in Chinese),2015,34(1):279-287.
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[13] 李军霞,汤达章,李培仁,等.中小尺度的多普勒径向速度场特征分析.气象科学,2007,27(5):557-563.LI Junxia,TANG Dazhang,LI Peiren,et al.Analysis of meso and small scale Doppler velocity features.Scientia Meteorologica Sinica(in Chinese),2007,27(5):557-563.
[14] 侯民胜,邹平,朱莹.FFT在现代雷达中的应用.电子测量技术,2009,32(4):9-11.HOU Minsheng,ZOU Ping,ZHU Ying.Apllications of FFT in modern radar.Electronic Measurement Technology (in Chinese),2009,32(4):9-11.
[15] 胡广书.数字信号处理.2版.北京:清华大学出版社,2003:59-61.HU Guangshu.Digital signal processing.2nd ed.Beijing:Tsinghua University Press(in Chinese),2003:59-61.
[16] 何毅,范艺,朱克云,等.DRSP和RVP8天气雷达信号处理效果定量分析.成都信息工程学院学报,2015,30(2):144-152.HE Yi,FAN Yi,ZHU Keyun,et al.The quantitative analysis of effect about doppler weather radar signal processor DRSP and RVP8.Journal of Chengdu University of Information Technology(in Chinese),2015,30(2):144-152.
[17] 张少波,陆汉城,康建伟.一次超级单体风暴多普勒天气雷达资料的低层风场反演研究.气象科学,2007,27(2):147-154.ZHANG Shaobo,LU Hancheng,KANG Jianwei.The lower level wind retrieval applied to a super cell storm using Doppler radar.Scientia Meteorologica Sinica(in Chinese),2007,27(2):147-154.
[2] 何宇翔,肖辉,吕达仁.利用极化雷达分析层状云中水凝物粒子性状分布.大气科学,2010,34(1):23-24.HE Yuxiang,XIAO Hui,LYU Daren.Analysis of hydrometeor distribution characteristics in stratiform clouds using polarization radar.Chinese Journal of Atmospheric Sciences (in Chinese),2010,34(1):23-24.
[3] Doviak R J,Bringi V,Ryzhkov A,et al.Considerations for polarimetric up grades to operational WSR-88D radars.J.Atmos.Ocean.Technol.,2000,17(3):257-278.
[4] Bringi V N,Chandrasekar V.偏振多普勒天气雷达原理和应用.李忱,张越,译.北京:气象出版社,2010:156.Bringi V N,Chandrasekar V.Polarimetric doppler weather radar:Principles and applications.LI Chen,ZHANG Yue,Trans.Beijing:China Meteorological Press(in Chinese),2010:156.
[5] 梁海河,徐宝祥,刘黎平,等.偏振微波雷达探测大气研究进展及几个问题的考虑.地球科学进展,2005,20(5):541-548.LIANG Haihe,XU Baoxiang,LIU Liping,et al.Evolvement of polarimetric technology detecting atmosphere and sone consideration of its problems.Advances in Earth Science(in Chinese),2005,20(5):541-548.
[6] 王致君.偏振气象雷达发展现状及其应用潜力.高原气象,2002,21(5):495-500.WANG Zhijun.The current developing situation of polarization radar and its application potential.Plateau Meteorology(in Chinese),2002,21(5):495-500.
[7] 魏洪峰,杜智涛,王洋.国内外新体制天气雷达发展动态综述.气象水文海洋仪器,2013,30(2):124-128.WEI Hongfeng,DU Zhitao,WANG Yang.Development status about domestic and foreign weather radar.Meteorological,Hydrological and Marine Instruments(in Chinese),2013,30(2):124-128.
[8] 孙宁,寿绍文,吴海英,等.用二步变分法反演的单多普勒雷达风场研究中尺度暴雨.气象科学,2009,29(6):768-774.SUN Ning,SHOU Shaowen,WU Haiying,et al.Meso-scale rainstorm analysis by retrieved wind field from single Doppler radar using twi-adjoint method.Scientia Meteorologica Sinica (in Chinese),2009,29(6):768-774.
[9] Gorgucci E,Scarchilli G,Chandrasekar V.A procedure to calibrate multiparameter weather radar using propertiesof the rain medium.IEEE Trans.Geosci.Remote.Sens.,1999,37(1):269-276.
[10] Gourley J J,Tabary P,Chatelet J P D.Data quality of the Meteo-France C-band polarimetric radar.J.Atmos.Ocean.Technol.,2006,23(10):1340-1356.
[11] 吴林林,刘黎平,袁野,等.C波段车载双偏振雷达ZDR资料处理方法研究.高原气象,2015,34(1):279-287.WU Linlin,LIU Liping,YUAN Ye,et al.Study on ZDR processing algorithm of C-band mobile dual polarization radar.Plateau Meteorology (in Chinese),2015,34(1):279-287.
[12] 胡志群,刘黎平,吴林林.C波段偏振雷达几种系统误差标定方法对比分析.高原气象,2014,33(1):221-231.HU Zhiqun,LIU Liping,WU Linlin.Comparison among several system biases calibration methods on C-band polarimetric radar.Plateau Meteorology (in Chinese),2014,33(1):221-231.
[13] 李军霞,汤达章,李培仁,等.中小尺度的多普勒径向速度场特征分析.气象科学,2007,27(5):557-563.LI Junxia,TANG Dazhang,LI Peiren,et al.Analysis of meso and small scale Doppler velocity features.Scientia Meteorologica Sinica(in Chinese),2007,27(5):557-563.
[14] 侯民胜,邹平,朱莹.FFT在现代雷达中的应用.电子测量技术,2009,32(4):9-11.HOU Minsheng,ZOU Ping,ZHU Ying.Apllications of FFT in modern radar.Electronic Measurement Technology (in Chinese),2009,32(4):9-11.
[15] 胡广书.数字信号处理.2版.北京:清华大学出版社,2003:59-61.HU Guangshu.Digital signal processing.2nd ed.Beijing:Tsinghua University Press(in Chinese),2003:59-61.
[16] 何毅,范艺,朱克云,等.DRSP和RVP8天气雷达信号处理效果定量分析.成都信息工程学院学报,2015,30(2):144-152.HE Yi,FAN Yi,ZHU Keyun,et al.The quantitative analysis of effect about doppler weather radar signal processor DRSP and RVP8.Journal of Chengdu University of Information Technology(in Chinese),2015,30(2):144-152.
[17] 张少波,陆汉城,康建伟.一次超级单体风暴多普勒天气雷达资料的低层风场反演研究.气象科学,2007,27(2):147-154.ZHANG Shaobo,LU Hancheng,KANG Jianwei.The lower level wind retrieval applied to a super cell storm using Doppler radar.Scientia Meteorologica Sinica(in Chinese),2007,27(2):147-154.